Balloon dilatation catheters are used for a variety of procedures in which a body lumen or vessel is dilated. For example, such catheters are used in percutaneous transluminal angioplasty procedures in which a stenosed region of an artery, such as a coronary artery, is widened by inserting a deflated balloon into the stenosis and then inflating the balloon under pressure to forcibly enlarge the lumen through the artery. After a brief period of time, the balloon is deflated and removed. Such catheters typically have an elongate flexible shaft and a balloon mounted at the distal end of the shaft. The shaft has a balloon inflation lumen that provides fluid communication between the proximal end of the catheter and the interior of the balloon at the distal end of the shaft.
Balloon catheters are typically actuated by manual syringes, often called “inflators” (or inflation devices), which use a plunger that is manually advanced using a rod that is threaded into a handle to allow the operator to advance the plunger using very small, controlled increments. Some syringes include a pressure gauge, but the gauge is often located on the syringe itself, and it therefore may be impractical for the physician to monitor the gauge as he or she tries to also watch an image of the balloon being inflated on a monitor. The process for setting up and operating a manual balloon inflation syringe creates logistical difficulties.
Automatic injection devices, such as described in U.S. Pat. No. 6,099,502, are known for delivering fluids such as saline and contrast agents through a catheter to a patient. The devices typically include a motor-driven linear actuator that forces a plunger through a syringe, thereby creating a desired fluid flow into the patient. For sanitation purposes, the syringe and all associated tubing between the patient and the syringe are disposable, which increases the expense of the system. Further, preparing the automatic injection device for operation can be a time-consuming process. Various tubes may need to be connected together and to the device. The operator preparing the injection device for operation must often be careful to ensure that the connections are tight and that none of the tubes are pinched or otherwise blocked.
Although numerous configurations are available for inflating balloon catheters, there is a need for a simpler system.